Days Between Dates Calculator
Count the exact number of days between two dates instantly. Our date difference calculator handles leap years, multi-year spans, and also returns the result in weeks, months, and total hours.
Days Between Dates Calculator
Enter two dates to count the exact number of days between them
What Is a Days Between Dates Calculator?
A days between dates calculator is a tool that tells you the exact number of calendar days separating two specific dates. Instead of manually counting squares on a calendar, you simply enter a start date and an end date and get an instant, precise answer — including leap year days that would throw off any mental calculation.
This date difference calculator is especially useful when you need to count days between two dates for contracts, project timelines, deadlines, travel planning, age verification, or any situation where precision matters. Counting days by hand is error-prone — a single missed leap year or incorrect month length can throw your count off by a day or more.
How to Calculate the Number of Days Between Two Dates
- 1Select your start date using the date picker in the calculator above.
- 2Select your end date. You can go forward or backward in time — any combination works.
- 3Click "Count Days Between Dates" to get the exact result.
- 4Read the main result (total days) plus the breakdown into weeks, months, and hours.
- 5Use the "Quick presets" buttons for common ranges like "Next 30 days" or "Last 90 days."
- 6Click "Copy" to copy the result as formatted text for use in emails, documents, or reports.
How Are Days Between Dates Calculated?
The formula to count days between two dates is:
Days = (End Date − Start Date) ÷ 86,400,000 millisecondsBoth dates are converted to milliseconds since January 1, 1970 (Unix epoch), subtracted, then divided by the number of milliseconds in a day. This approach automatically accounts for leap years, since leap days add real milliseconds to the calendar.
Common Use Cases for Counting Days Between Dates
Examples: Number of Days Between Two Dates
Frequently Asked Questions
How do I calculate the number of days between two dates?
Enter your start date and end date into the calculator above, then click "Count Days Between Dates." The tool instantly returns the exact number of days, plus the equivalent count in weeks, months, and hours.
Does the days between dates calculator include both the start and end date?
By default, the calculator counts the gap between the two dates, not including the start day itself. For example, from January 1 to January 5 returns 4 days. To include both endpoints, add 1 to the result.
Can I calculate days between dates in the past?
Yes. You can enter any historical start date and any end date — past, present, or future. If the end date is before the start date, the calculator notes this and still returns the correct day count.
How many days between dates in different years?
The calculator handles multi-year spans automatically, accounting for leap years (366-day years). For example, the difference between January 1, 2020 and January 1, 2024 is 1,461 days because there are two leap years in between.
What is the difference between calendar days and business days?
Calendar days count every day of the week including weekends. Business days (also called working days) exclude Saturdays, Sundays, and public holidays. Use our Working Days Calculator if you need to count business days specifically.